1,2,4- and 1,3,4-Oxadiazoles as Scaffolds in the Development of Antiparasitic Agents

In this review, we present the potential use of the heterocyclic oxadiazole rings in the design and synthesis of new drugs to treat parasitic infections. We intend to compare herein all the four isomeric forms of oxadiazole rings as well as discuss the differences and similarities between them. In addition, we discuss aspects on their reactivity that justify the great importance of both 1,2,4- and 1,3,4-oxadiazoles isomers when compared with their other two isomers. Although some oxadiazole isomers satisfy Huckel's rule, there are differences concerning their aromaticity, which have a great impact on the possible interactions of the oxadiazole ring with biological receptors. The set of works selected from the literature and discussed herein points out the oxadiazole core as an important and versatile scaffold in the development of new chemical entities potentially useful as antiparasitic drugs.